Spark suppressor resistor



G. M. EHLERs SPARK SUPPRESSOR RESISTOR July 18, 1939.

.Filed June 19, 4193s IN VENT OR.

ATTORNEY.

Patented July 18, 1939 UNITED STATES PATENT OFFICE SPARK SUPPRESSOR RESISTOR Application June 19, 1936, Serial No. 86,059

1 Claim.

This invention relates to a resistor especially designed and adapted for use in suppressing oscillations set up in ignition systems of internal combustion engines and of the character disturbing to radio reception.

In the application of Adelbert R. Morton, iiled September 25, 1935, for Spark suppressor resistors, Serial No. 42,003, and assigned to the same assignee as the present application, a resistor of this general character is disclosed and generally proposes an organization of insulating housing, resistor and terminals designed to achieve a very high degree of compactness. Compactness was achieved by employing a ceramic insulated resistor not only enclosed in the insulated housing but accommodated for a considerable portion of its length in a hollow portion of one of the terminals. These terminals were pressed into the open ends of a cylindrical insulating tube and on account of their axial alinement approached' within a short distance of one another inside the insulating housing.

It has been found that if resistance values exceeding 20,000 ohms are thus mounted in a housing and inserted in the high tension leads of an ignition system, the voltage drop between the terminals may cause a spark to jump between the terminals inside the insulating housing, thus defeating the purpose of the resistor. In some cases resistance values of the order 50,000 ohms are required in such spark oscillation supressing resistors.

One of the objects of the present invention is to provide a resistor adapted for spark oscilla.- tion suppression, one which retains all of the advantages of previously known structures of this character, which further shortens the overall length of the device and which eliminates the possibility of a spark passing or jumping between the terminals inside the insulating house.

The structura1 organization of the insulating housing, resistor and terminals is such that a portion of the insulator comprising the housing is directly interposed between the terminals thus preventing sparking between said terminals and consequent vitiating of the eifectiveness of the resistor.-

Another object is to provide a new and convenient method of securing the threaded ttings of the resistor in position in the insulating housing.

Other objects and advantages reside in certain novel features of the construction, arrangement and combination of parts which will be hereinafter more fully described and particularly pointed out in the appended claim, reference being had to the accompanying drawing forming a part of this specication, and in which:

Figure 1 is a view in central longitudinal section showing a spark suppressor resistor embodying the present invention and adapted to be incorporated in the ignition system of an internal combustion engine, the resistor being the type adapted to be screwed on the stud of the conventional spark plug and also adapted to receive the socket usually provided on the end of the high tension cable, parts of the resistor being shown in elevation for the sake of simplicity in illustration;

Figure 2 is a View in section taken on line 2 2 of Figure l;

Figure 3 is a view in end elevation looking toward the left hand end of Figure 1;

Figure 4 is a view in elevation illustrating a slight modication of the structure shown in Figure 1 in that the resistor is equipped with an adaptor bracket whereby it may be mounted vertically or horizontally on the threaded stud of the spark plug;

Figure 5 is a view partly in side elevation and partly in central longitudinal section showing an embodiment of the invention adapted to be incorporated in the high tension cable itself;

Figure 6 is a View in side elevation, a portion being broken away for the sake of illustration and showing a resistor of the type illustrated in Figure 1, save that the means for attaching the resistor to the spark plug is of the split ring type adapted to snap over the newer type of spark plug terminal which has a projecting stud with a rounded enlarged end instead of the threaded stud of the older type;

Figure l is a View partly in side elevation and partly in central longitudinal section showing a resistor of the type illustrated in Figure 6, save that the terminal adapted for connection to the high tension cable is in the form of a screw adapted to be threaded into the high tension cable itself; and

Figure 8 is a View in side elevation, parts being broken away and shown in section for the sake of illustration and illustrating a resistor of the type shown in Figure 1 but equipped with ttings designed to cooperate with a resilient head and a socket, respectively, and hence adapted for use with the distributor of the ignition system.

Referring to the drawing, and more especially to Figures 1 to 3, inclusive, it will be seen that in the embodiment of the resistor there illustrated an insulating housing I is provided. The

housing may be constituted of any suitable insulating composition or material but is preferably a phenol condensation product such as molded Bakelite. As will be understood from Figure 2, the housing has a portion 2 of substantiaily cylindrical form and integral therewith is provided with a lateral extension 3 of reduced cross sectional area. The extension 3 is provided with an axial opening 4 extending from end to. end thereof. A resistor 5 is tted in this opening :i and occupies substantially the entire longitudinal extent thereof although terminating just short of the ends for purposes which will hereinafter appear. This resistor 5 embodies the construction disclosed in my pending application led December 4, 1933, Serial No. 700,872, which has matured into Patent Number 2,084,840 and, as more fully described in said application, com-v prises a conducting core 6 surrounded by a ceramic insulated jacket l and having metal conducting layers 3 and 9 sprayed on its ends and in electrical connection with the conducting core 5.

An internally threaded terminal lo is iitted in an opening il provided therefor in one end of the main portion 2 of the insulating'housing. This terminal is in the form of a metal cup closed at its inner end and having its inner closed end riveted or otherwise suitably secured as at it to a sheet metal attaching spider or bracket designated generally at 55. This spider it has a plurality of integral retaining tongues cr fingers ifi which embrace tne sides ofthe cuplike terminal lil and are themselves received in grooves or channels l5 provided therefor in the wall of the opening il. The retaining tongues ifi are forced tightly into the housing and at least two of them may be bent slightly outwardly to have binding engagement with the housing. The channels or grooves i5 in some instances be omitted. intermediate the fingers id the attaching spider may also be provided with tangs i@ which are angled and designed to bite into the wall of the opening li to securely hold the terminal i@ in position. One of the fingers ifi is provided with an angular extension il which extends over and bears against the conductive end layer 9 of the resistor e to establish good electrical connection therewith.

The end of the main section 2 of the insulating housing opposite that with which the terminal iii is associated is provided with an axial opening 2d into which a stud-like terminal 2l is tightly and securely fitted. In the construction shown the terminal has a plurality of integral serrated or knurled collars which are a tight binding iit in the recess or axial opening Extcrnally the terminal 2i has a threaded portion 253. The stud-like terminal Zi is provided with an integral or rigidly connected' shoulder which, in the assembly, holds a connector plate 25 rmly in position. This connector plate 25 extends over the adjacent end of the opening il and provides an abutment for one end of a coil spring 2s, the other end of which engages the metallic end layer 8 of the resistor 5. The spring'g, in this and other embodiments of the invention, insures good electrical contact between the ends of the resistor 5 and the connector plates extending from the terminals.

v It is to be understood, of course, that certain of the advantages oithe present invention may be realized if one of the terminals, for example, the terminal stud is molded in the housing, the 'resistor i5 the remaining terminal l0 being assembled with the molded housing in the* manner described. However, from the standpoint of manufacture it. is at the present time more convenient and preferable to obtain the molded housing l with. its various openings or recesses molded therein and. assemble the resistor, terminals and other elements therewithin the manner described.

One of the important features' of the invention resides in the fact that there is a substantial imperforate portion 2l of the insulating molded housing directly interposed between the terminals l and 2l. This. provides an insulating barrier effectively precludes a spark jumping between these terminals and constrains the current to iiow through the resistor 5.

The form of the invention shown in Figure 4 is identical with that just described and the foregoing description applies thereto, save that the metal terminal cup lli and its attaching spider are omitted. In lieu thereof a terminal stud designated generally at 3G which has knurled collars 3iy is a driving t in a recess 32 formed in the same end of the casing as the recess H but of somewhat smaller cross sectional dimensions. The head of this stud is riveted to a U-shaped attaching tting 33 which has right angularly extending portions 34 and 35 provided With attaching openings 35 and El adapting it for connection wtih the stud of a spark plug in such manner that the resistor is either vertically or horizontally disposed. The head of the stud 30 secures inV position a connecting plate 38 which contacts with one end of the resistor 5. As in the other embodiment of the invention, a substantial imperforate portion 39v of the insulating housing is directly interposed between the terminals 2l and Si! so as to constrain the current to flow through the resistor 5..

In the embodiment of the invention illustrated in FigureV the insulating ybody of the resistor is designated at ld and as before has-amain section and a lateral extension 4 2. In an axial opening 413` extending from end to end' of the lateral extension 42 a resistor 5 is fitted as before. In this embodiment of thev invention the terminals designated at 4,41 and' 45 take the formof pointedvv screws similarto wood screws. These screw terminals are adapted to be threaded or screwed in to the'high tension cable itself. They are respectively accommodated in openings 46 and 4l provided in the opposite ends ofthe main sections 4lV of the insulating body. Between these terminals isan imperforate insulating barrier 58 constituted by an integral portion of the insulating housing. Each screw is held in position in its recess or opening by means of an attaching or mounting spider 59; These spiders are' ofidentical construction and each has a body portion 5l to which the inner end of its screw is riveted; Retaining tongues 52 extend forwardly and outwardly from the bodyI of each spider and bite into the inner wall of the opening in which it is accommodated to hold? the terminal against outward displacement, One of the tongues of each spider 50 is provided with an angular extension 53 which overlaps the adjacent end of the opening 453 so as to be adapted for electrical connection either with the metallic end of the resistor or with aspring 26 interposed between one end of the resistor and one of these angular connectors.

The embodiment of the invention shown in Figure 6 is similar except for the speciiic terminal. constructions to that shown in Figure 4.

One of the terminals designated at instead of having an externally threaded projecting portion is riveted to a combined connector and spring clip 56 which is adapted to be snapped over the rounded enlarged end of the projecting stud of a newer type of spark plug terminal. The flat attaching portion of the clip bears against the spring between it and the adjacent end of the resistor 5. The other terminal 51 is adapted to be threaded into the socket of a high tension cable. The terminals are driving ts in openings provided therefor in the housing and are sepan rated by an insulating barrier 58. They are connected with the ends of the resistor 5 as before.

In the form of the invention shown in Figure 7, a spring clip such as shown at 56 in Figure 6 is employed but in lieu of the terminal 5'? a pointed screw terminal 50 identical with the terminals 44 and 45 is provided at the other end of the resistor. An insulating barrier 59 is interposed between the terminals as in the other embodiments of the invention. Also the resistor 5 is related and combined with the terminals 56 and 60 as before.

The form of the invention shown in Figure 8 is identical with that shown in Figure 6 except for the different types of terminal ttings. As illustrated in Figure 8, one of the terminals designated at iii is provided with a socket type fitting 62 and the other terminal 63 with a resilient head type fitting E4 designed to be introduced into a socket similar to the socket 62. This .arrangement adapts this type of resistor for convenient use at the distributor. As in the other embodiments of the invention, the terminals have interposed between them an insulating barrier 65 and they are combined and electrically connected with the resistor 5 as before.

In all of the various embodiments of the invention the resistor has a minimum overall length, that is, it realizes the advantage of compactness to the highest degree. The construction is simple and readily fabricated and this with economy. However, in all forms of the invention the possibility of the spark jumping between the terminals and short circuiting the resistor is precluded.

While I have shown and described several constructions in which the invention has been advantageously embodied it is to be understood that these constructions have been selected merely for the purpose ol illustration or example and that various changes in the size, shape and arrangement of the parts may be made without departing from the spirit of the invention or the scope of the subjoined claim.

The invention claimed is:

A spark suppressor resistor comprising an insulating housing having a main portion in substantially cylindrical form and integral thereof a lateral extension of reduced cross-sectional area, an opening extending from end to end of said extension, a resistor in said opening substantially coextensive therewith, recesses extending from opposite ends of said main portion and terminating at spaced points to provide an insulating barrier therebetween, said recesses adapted to receive and securely engage anchoring portions of metal terminals, metal terminals held in said recesses, metal connectors secured to said termifnals and extending to and overlying the ends of the openings through said extension, and a spring fitted between one of said connectors and one end of said resistor.

GEORGE M. EHLERS. 

